Those Confusing Leaves of Three

In our continuing story of ‘paying closer attention to what’s going on at home,’ the subject of identifying poison ivy (Toxicodendron radicans) came up while talking with my neighbor recently. She had gotten into some accidentally and was concerned with properly identifying it so as to at least avoid it if not actually get rid of it.

Virgin's bower (Clematis virginiana) - 3 leaflets but leaves are in pairs

Young blackberry (Rubus sp.) - prickles are a clue

Many plants either have ‘leaves of 3’ or appear to have them.  To help her learn, I created a small exhibit for her: there was a poison ivy seedling in my yard (close to hers) so I marked it and then put two lookalike sprigs in floral picks next to it: Virgin’s bower clematis (Clematis virginiana) which is very common in our yards, and one of the young wild blackberries (Rubus sp.), also very common. In the spirit of distancing, I told her where to find this exhibit on her own so she could look at the plants.

That got me thinking about how confusing being in the woods must be when you aren’t sure what you are seeing. I walked around my property, taking pictures of many of the things that appear to have 3 leaves. First, it’s good to understand basic concepts: 1) simple leaves vs. compound leaves (poison ivy actually has compound leaves); and 2) leaf arrangement (opposite vs. alternate, poison ivy’s compound leaves are alternate). Here’s an old but basic post that I did about that, so check it out.

Trumpet creeper sprout (Campsis radicans),
notice that more mature leaves have more leaflets

Green ash seedling (Fraxinus pennsylvanica); older
leaves will get more leaflets but new ones may have only 3

Here are a few pictures (there were more, believe me!) of what I found just walking around like my neighbor might be doing. Of course what is even more confusing is finding atypical leaves of anything. We’ve all got a story of finding 3-leaved versions of the normally 5-leaved Virginia creeper (Parthenocissus quinquefolia). They usually don’t persist over the whole plant, sometimes it is just the most recent growth and if you follow it back then you should find some growth with the ‘true’ leaf forms. Sometimes young plants have few leaflets (see examples above). I found many examples of hickory (Carya sp.) doing the same thing.

Hog peanut (Amphicarpaea bracteata)

Yellowroot (Xanthorhiza simplicissima)

Not always obvious is the concept of woody vs. herbaceous. Poison ivy is a woody plant and will eventually have a woody stem (even as a second year seedling). There are herbaceous plants (not woody) that have the 3-leaf look: Jack-in-the pulpit (Arisaema triphyllum) and trilliums (Trillium sp.) are two that quickly come to mind. Of course a first year seedling poison ivy won't be woody but it's something to consider when you find 6-inch-plus tall plants like these below and they have soft stems.

Jack-in-the-pulpit (Arisaema triphyllum)

Trillium rugelii

Another concept that I’d like to mention particularly in regards to seedlings - and specifically Virginia creeper (Parthenocissus quinquefolia) seedlings compared to poison ivy seedlings. I see tons of seedlings in my yard, and, in the spring, I often see just the cotyledon leaves. What are those? They are the first leaves to appear from a germinating seed. They don’t usually have the shape of the ‘true’ leaves that follow. They can appear in pairs even if the plant doesn’t later have pairs of leaves (the opposite leaf arrangement). For plants with alternate leaf arrangement, the next leaf—the first true leaf—will appear as a single leaf; for plants with opposite leaf arrangement, the next growth will be a pair of leaves (we’ve all seen those seedling maples (opposite) and sweetgums (alternate) grow like this).

Cotyledons - the first seedling leaves - are different for poison ivy and Virginia creeper;
notice the non-standard Virginia creeper in the center but the baby leaves give it away

Virginia creeper has heart-shaped cotyledon leaves, as shown in the center and right pictures above. Grapes, like muscadine, do as well. My woods are full of both of these—hundreds and hundreds of tiny heart-shaped leaves …. These two plants are both in the grape (Vitaceae) family and that resemblance comes through in their cotyledon leaves. Poison ivy is in a different family and has very simple, like a rounded rectangle, set of cotyledon leaves. Notice the incorrect set of 3 leaflets on the Virginia creeper in the center; Virginia creeper can sometimes show only 3 leaflets on a few of its leaves.

Lastly, should you think you encountered poison ivy (or even to be extra careful), I recently came across some good advice. Don't just wash with soap and water to remove the ivy's oil, use a washcloth to add friction to the cleaning. Our hands alone don't provide enough friction to remove all the oil but a washcloth will greatly improve your efforts. Be sure to take that washcloth (and any clothing you wore) straight to the washing machine to avoid re-infecting yourself later.

The real thing: Poison ivy (Toxicodendron radicans)

A healthy, flowering poison ivy vine (flowers kind of hidden by leaves)